S. Abubakar, M. A. Acero, B. Acharya, P. Adamson, N. Anfimov, A. Antoshkin, E. Arrieta-Diaz, L. Asquith, A. Aurisano, D. Azevedo, A. Back, N. Balashov, P. Baldi, B. A. Bambah, E. F. Bannister, A. Barros, A. Bat, R. Bernstein, T. J. C. Bezerra, V. Bhatnagar, B. Bhuyan, J. Bian, A. C. Booth, R. Bowles, B. Brahma, C. Bromberg, N. Buchanan, A. Butkevich, S. Calvez, T. J. Carroll, E. Catano-Mur, J. P. Cesar, S. Chaudhary, R. Chirco, S. Choate, B. C. Choudhary, O. T. K. Chow, A. Christensen, M. F. Cicala, T. E. Coan, T. Contreras, A. Cooleybeck, D. Coveyou, L. Cremonesi, G. S. Davies, P. F. Derwent, P. Ding, Z. Djurcic, K. Dobbs, M. Dolce, D. Dueñas Tonguino, E. C. Dukes, A. Dye, R. Ehrlich, E. Ewart, G. J. Feldman, P. Filip, M. J. Frank, H. R. Gallagher, F. Gao, A. Giri, R. A. Gomes, M. C. Goodman, R. Group, A. Habig, F. Hakl, J. Hartnell, R. Hatcher, J. M. Hays, M. He, K. Heller, V. Hewes, A. Himmel, T. Horoho, X. Huang, A. Ivanova, B. Jargowsky, I. Kakorin, A. Kalitkina, D. M. Kaplan, A. Khanam, B. Kirezli, J. Kleykamp, O. Klimov, L. W. Koerner, L. Kolupaeva, R. Kralik, A. Kumar, C. D. Kuruppu, V. Kus, T. Lackey, K. Lang, J. Lesmeister, A. Lister, J. Liu, J. A. Lock, M. MacMahon, S. Magill, W. A. Mann, M. T. Manoharan
This Letter reports measurements of muon-neutrino disappearance and electron-neutrino appearance and the corresponding antineutrino processes between the two NOvA detectors in the NuMI neutrino beam. These measurements use a dataset with double the neutrino mode beam exposure that was previously analyzed, along with improved simulation and analysis techniques. A joint fit to these samples in the three-flavor paradigm results in the most precise single-experiment constraint on the atmospheric neutrino mass splitting, Δm_{32}^{2}=2.431_{-0.034}^{+0.036}(-2.479_{-0.036}^{+0.036})×10^{-3} eV^{2} if the mass ordering is normal (inverted). In both orderings, a region close to maximal mixing with sin^{2}θ_{23}=0.55_{-0.06}^{+0.02} is preferred. The NOvA data show a mild preference for the normal mass ordering with a Bayes factor of 2.4 (corresponding to 70% of the posterior probability), indicating that the normal ordering is 2.4 times more probable than the inverted ordering. When incorporating a 2D Δm_{32}^{2}-sin^{2}2θ_{13} constraint based on Daya Bay data, this preference strengthens to a Bayes factor of 6.6 (87%).